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nuckolls.bob(at)aeroelect
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 Posted: Mon Apr 19, 2010 7:16 am Post subject: Facet pumps: Energy vs. Flow |
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Good Morning 'Lectric Bob,
This discussion of controlling a circuit by noting the change in power consumption has gotten me to think a bit and that is always dangerous.
But exciting too! Fortunately much less hazardous than
inverted flight 6' off the runway . . .
My electrical knowledge is miniscule, but I can generally understand the principles once they have been explained by you and the other good instructors on this list.
I have the desire to know when fuel stops flowing from one tank to another tank via an electric pump.
In other words, I would like to know when all of the fuel from a tank has been transferred. My transfer system uses a Facet plunger style pump and as the tank runs dry, the sound of the pump changes.
Unfortunately, I can only hear the pump running when I am parked on the ground with my engine shut down. I have tried to monitor the total system amperage load to see if I could detect the change when a tank runs dry, but the load seems to oscillate enough that I cannot pick it up via that instrument. I am using an E.I. VA-1A to monitor the alternator output.
Is there a simple and, hopefully, economical way to measure the amount of current it takes to drive the pump or is there a better way to tell when fuel is no longer being transferred? I have thought of using a pressure gauge in the fuel line, but maybe it would be easier to measure the change in current draw of the fuel pump?
Facet says that the pump can be run dry for a short period of time, but they will not specify how long that time can be!
I hate to run my pump when it is operating dry. An indicator light to tell me it is running dry would sure be helpful. <G>
Any help available is sincerely appreciated.
I've not studied the Facet pumps but waaayyyy back
when, the Bendix thump-thump pumps were king. Those
pumps used a solenoid to "cock" a spring that in
turn put pressure on the fuel. Selecting a spring
tension sets the fuel pump's output pressure. When
the plunger bottoms out, contacts close to energize
the solenoid thus re-cocking the spring for the
next stroke.
Obviously, the current draw of this device is
constant . . . it's a function of applied voltage
and coil resistance of the solenoid. So if we're
to remain faithful to the laws of conservation of
energy, then the thing that changes for pump
load is FREQUENCY. The lower the back pressure,
the faster the pump cycles for each stroke. Maximum
frequency occurs when the back pressure went to zero.
Do the Facets do the same thing? I've had a pump
laying here for several years. Somebody sent me one
to do an energy study at various pressures and
flows for a load analysis . . . never got around
to setting it up. Probably ought to do that.
It would be cool if we could get the Facet patent
numbers to look up their operating principals.
Bob . . . [quote][b]
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BobsV35B(at)aol.com
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| Posted: Mon Apr 19, 2010 10:41 am Post subject: Facet pumps: Energy vs. Flow |
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Good Afternoon 'Lectric Bob,
To me, they look and sound just like the ones that were used on those Ford gasoline fired heaters back in the thirties. But my memory could be fooling me.
Those were probably the Stewart Warner or Bendix pumps. Whadda Ya Think?
If so. does that mean I need to monitor the frequency some how?
This is getting complicated,. No wonder nobody does it!
Happy Skies,
Old Bob
In a message dated 4/19/2010 10:17:33 A.M. Central Daylight Time, nuckolls.bob(at)aeroelectric.com writes:
| Quote: | Good Morning 'Lectric Bob,
This discussion of controlling a circuit by noting the change in power consumption has gotten me to think a bit and that is always dangerous.
But exciting too! Fortunately much less hazardous than
inverted flight 6' off the runway . . .
My electrical knowledge is miniscule, but I can generally understand the principles once they have been explained by you and the other good instructors on this list.
I have the desire to know when fuel stops flowing from one tank to another tank via an electric pump.
In other words, I would like to know when all of the fuel from a tank has been transferred. My transfer system uses a Facet plunger style pump and as the tank runs dry, the sound of the pump changes.
Unfortunately, I can only hear the pump running when I am parked on the ground with my engine shut down. I have tried to monitor the total system amperage load to see if I could detect the change when a tank runs dry, but the load seems to oscillate enough that I cannot pick it up via that instrument. I am using an E.I. VA-1A to monitor the alternator output.
Is there a simple and, hopefully, economical way to measure the amount of current it takes to drive the pump or is there a better way to tell when fuel is no longer being transferred? I have thought of using a pressure gauge in the fuel line, but maybe it would be easier to measure the change in current draw of the fuel pump?
Facet says that the pump can be run dry for a short period of time, but they will not specify how long that time can be!
I hate to run my pump when it is operating dry. An indicator light to tell me it is running dry would sure be helpful. <G>
Any help available is sincerely appreciated.
I've not studied the Facet pumps but waaayyyy back
when, the Bendix thump-thump pumps were king. Those
pumps used a solenoid to "cock" a spring that in
turn put pressure on the fuel. Selecting a spring
tension sets the fuel pump's output pressure. When
the plunger bottoms out, contacts close to energize
the solenoid thus re-cocking the spring for the
next stroke.
Obviously, the current draw of this device is
constant . . . it's a function of applied voltage
and coil resistance of the solenoid. So if we're
to remain faithful to the laws of conservation of
energy, then the thing that changes for pump
load is FREQUENCY. The lower the back pressure,
the faster the pump cycles for each stroke. Maximum
frequency occurs when the back pressure went to zero.
Do the Facets do the same thing? I've had a pump
laying here for several years. Somebody sent me one
to do an energy study at various pressures and
flows for a load analysis . . . never got around
to setting it up. Probably ought to do that.
It would be cool if we could get the Facet patent
numbers to look up their operating principals.
Bob . . . | Quote: |
====================================
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ms.matronics.com/">http://forums.matronics.com
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tp://www.matronics.com/contribution">http://www.matronics.com/contribution
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[quote][b]
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mrspudandcompany(at)veriz
Guest
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| Posted: Mon Apr 19, 2010 12:07 pm Post subject: Facet pumps: Energy vs. Flow |
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To me, they look and sound just like the ones that were used
on those Ford gasoline fired heaters back in the thirties. But my memory
could be fooling me.
Those were probably the Stewart Warner or Bendix pumps.
Whadda Ya Think?
If so. does that mean I need to monitor the frequency some
how?
This is getting complicated,. No wonder nobody does it!
Happy Skies,
Old Bob
I am not sure of the application here, but I
believe that there should be a significant pressure drop on the output of
the pump, when there is no longer any fuel. This being the case, perhaps
you could use a pressure switch, similar to what is used to monitor engine
oil pressure and turn on the hobbs meter, on some aircraft. You would need
to check the pressure differential between pumping fuel and empty tank
pumping, and use a switch midway between. This would be a normally closed
switch which would open when there is fuel flow and close, to turn on the
light when there is no more fuel to pump.
Not sure if this is a viable option for your
application, but might work, and is very simple. (I especially like
simple:-)
Roger
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BobsV35B(at)aol.com
Guest
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| Posted: Mon Apr 19, 2010 1:32 pm Post subject: Facet pumps: Energy vs. Flow |
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Good Afternoon Roger,
That is the path I was exploring before I read the idea of using the amount of current needed to monitor a circuit. Just thought the electrical solution might be simpler than using pressure. So far, I have not found a source for pressure switches that will activate at the very low pressures involved. I don't have exact numbers as yet, but it seems we will need to be able to tell the difference between one PSI and about two PSI.
So far, that optical device seems the best, but I want to use this on a certificated aircraft. Consequently, a pressure switch or anything else that is put in the fuel system probably has to meet certification standards. Just measuring the current could be considered as a Part 43 acceptable monitor.
Happy Skies,
Old Bob
In a message dated 4/19/2010 3:09:52 P.M. Central Daylight Time, mrspudandcompany(at)verizon.net writes:
| Quote: |
To me, they look and sound just like the ones that were used
on those Ford gasoline fired heaters back in the thirties. But my memory
could be fooling me.
Those were probably the Stewart Warner or Bendix pumps.
Whadda Ya Think?
If so. does that mean I need to monitor the frequency some
how?
This is getting complicated,. No wonder nobody does it!
Happy Skies,
Old Bob
I am not sure of the application here, but I
believe that there should be a significant pressure drop on the output of
the pump, when there is no longer any fuel. This being the case, perhaps
you could use a pressure switch, similar to what is used to monitor engine
oil pressure and turn on the hobbs meter, on some aircraft. You would need
to check the pressure differential between pumping fuel and empty tank
pumping, and use a switch midway between. This would be a normally closed
switch which would open when there is fuel flow and close, to turn on the
light when there is no more fuel to pump.
Not sure if this is a viable option for your
application, but might work, and is very simple. (I especially like
simple:-)
Roger
|
[quote][b]
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ceengland(at)bellsouth.ne
Guest
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| Posted: Mon Apr 19, 2010 1:48 pm Post subject: Facet pumps: Energy vs. Flow |
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On 4/19/2010 3:03 PM, ROGER & JEAN CURTIS wrote:
| Quote: |
To me, they look and sound just like the ones that were used
on those Ford gasoline fired heaters back in the thirties. But my memory
could be fooling me.
Those were probably the Stewart Warner or Bendix pumps.
Whadda Ya Think?
If so. does that mean I need to monitor the frequency some
how?
This is getting complicated,. No wonder nobody does it!
Happy Skies,
Old Bob
I am not sure of the application here, but I
believe that there should be a significant pressure drop on the output of
the pump, when there is no longer any fuel. This being the case, perhaps
you could use a pressure switch, similar to what is used to monitor engine
oil pressure and turn on the hobbs meter, on some aircraft. You would need
to check the pressure differential between pumping fuel and empty tank
pumping, and use a switch midway between. This would be a normally closed
switch which would open when there is fuel flow and close, to turn on the
light when there is no more fuel to pump.
Not sure if this is a viable option for your
application, but might work, and is very simple. (I especially like
simple:-)
Roger
If you're using it as a transfer pump, there won't be a lot of pressure
|
since it will be just the 'head' from one tank to the other. Often no
more than a few inches of rise, plus the resistance of the tubing.
How about one of the sensing devices using light to detect the presence
of liquid? I bought a couple several years ago, intending to use them to
monitor end-of-transfer from my aux tanks, then forgot to install
them.... They mount in a single hole & have a cone shaped plexi tip. An
LED shines out through the plexi; presence/absence of liquid changes the
light reflected back into the photocell in the same housing, changing
the state of the sense line.
If that interests you, I'll try to locate the name of the device & a
source for you.
Charlie
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BobsV35B(at)aol.com
Guest
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| Posted: Mon Apr 19, 2010 3:28 pm Post subject: Facet pumps: Energy vs. Flow |
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Good Morning Charlie,
Those units by Pillar Point Electronics look very promising. As I said a couple of messages back, I need something that can be used on a normally certificated aircraft. Not sure about the PPE product, but I am checking into it.
Thanks for the comment.
Happy Skies,
Old Bob
In a message dated 4/19/2010 4:50:49 P.M. Central Daylight Time, ceengland(at)bellsouth.net writes:
| Quote: | --> AeroElectric-List message posted by: Charlie England <ceengland(at)bellsouth.net>
On 4/19/2010 3:03 PM, ROGER & JEAN CURTIS wrote:
| Quote: |
To me, they look and sound just like the ones that were used
on those Ford gasoline fired heaters back in the thirties. But my memory
could be fooling me.
Those were probably the Stewart Warner or Bendix pumps.
Whadda Ya Think?
If so. does that mean I need to monitor the frequency some
how?
This is getting complicated,. No wonder nobody does it!
Happy Skies,
Old Bob
I am not sure of the application here, but I
believe that there should be a significant pressure drop on the output of
the pump, when there is no longer any fuel. This being the case, perhaps
you could use a pressure switch, similar to what is used to monitor engine
oil pressure and turn on the hobbs meter, on some aircraft. You would need
to check the pressure differential between pumping fuel and empty tank
pumping, and use a switch midway between. This would be a normally closed
switch which would open when there is fuel flow and close, to turn on the
light when there is no more fuel to pump.
Not sure if this is a viable option for your
application, but might work, and is very simple. (I especially like
simple:-)
Roger
If you're using it as a transfer pump, there won't be a lot of pressure
|
since it will be just the 'head' from one tank to the other. Often no
more than a few inches of rise, plus the resistance of the tubing.
How about one of the sensing devices using light to detect the presence
of liquid? I bought a couple several years ago, intending to use them to
monitor end-of-transfer from my aux tanks, then forgot to install
them.... They mount in a single hole & have a cone shaped plexi tip. An
LED shines out through the plexi; presence/absence of liquid changes the
light reflected back into the photocell in the same housing, changing
the state of the sense line.
If that interests you, I'll try to locate the name of the device & a
source for you.
Charlie
|
[quote][b]
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ceengland(at)bellsouth.ne
Guest
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| Posted: Mon Apr 19, 2010 6:05 pm Post subject: Facet pumps: Energy vs. Flow |
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Certificated. Bummer.
If you think you can legally use current sensing, have you tried a
restricter in the pump's output to see if it will raise the current
enough to be measurable vs the no-flow state?
On 4/19/2010 6:16 PM, BobsV35B(at)aol.com wrote:
| Quote: | Good Morning Charlie,
Those units by Pillar Point Electronics look very promising. As I said
a couple of messages back, I need something that can be used on a
normally certificated aircraft. Not sure about the PPE product, but I
am checking into it.
Thanks for the comment.
Happy Skies,
Old Bob
In a message dated 4/19/2010 4:50:49 P.M. Central Daylight Time,
ceengland(at)bellsouth.net writes:
<ceengland(at)bellsouth.net>
On 4/19/2010 3:03 PM, ROGER & JEAN CURTIS wrote:
>
> To me, they look and sound just like the ones that were used
> on those Ford gasoline fired heaters back in the thirties. But
my memory
> could be fooling me.
>
> Those were probably the Stewart Warner or Bendix pumps.
> Whadda Ya Think?
>
> If so. does that mean I need to monitor the frequency some
> how?
>
> This is getting complicated,. No wonder nobody does it!
>
> Happy Skies,
>
> Old Bob
>
> I am not sure of the application here, but I
> believe that there should be a significant pressure drop on the
output of
> the pump, when there is no longer any fuel. This being the
case, perhaps
> you could use a pressure switch, similar to what is used to
monitor engine
> oil pressure and turn on the hobbs meter, on some aircraft. You
would need
> to check the pressure differential between pumping fuel and
empty tank
> pumping, and use a switch midway between. This would be a
normally closed
> switch which would open when there is fuel flow and close, to
turn on the
> light when there is no more fuel to pump.
>
> Not sure if this is a viable option for your
> application, but might work, and is very simple. (I especially like
> simple:-)
>
> Roger
>
If you're using it as a transfer pump, there won't be a lot of
pressure
since it will be just the 'head' from one tank to the other. Often no
more than a few inches of rise, plus the resistance of the tubing.
How about one of the sensing devices using light to detect the
presence
of liquid? I bought a couple several years ago, intending to use
them to
monitor end-of-transfer from my aux tanks, then forgot to install
them.... They mount in a single hole & have a cone shaped plexi
tip. An
LED shines out through the plexi; presence/absence of liquid
changes the
light reflected back into the photocell in the same housing, changing
the state of the sense line.
If that interests you, I'll try to locate the name of the device & a
source for you.
Charlie
*
*
|
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rampil
Joined: 04 May 2007
Posts: 870
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| Posted: Tue Apr 20, 2010 4:40 am Post subject: Re: Facet pumps: Energy vs. Flow |
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Good engineering principles favor measuring the actual parameter
you want, rather than a surrogate, especially when there is no
reliable one-to-one mapping of one to the other.
In the case of current draw, for example, overheating the coil or dirt
in the mechanism will probably change the current draw
Pressure downstream would depend on where the fill hose enters the
downstream tank, if at the bottom, or at a positive hydrostatic head, the
pressure downstream of the pump will stay positive while there is fuel
in the tank.
What about measuring fuel level in the feeding tank, is not that what you
really want to make a decision with? When it reads zero, stop pumping?
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jonlaury
Joined: 06 Nov 2006
Posts: 336
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| Posted: Wed Apr 21, 2010 7:49 am Post subject: Facet pumps: Energy vs. Flow |
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Check out Gems Sensors and this optical sensor:
http://www.gemssensors.com/content.aspx?id=5432
I got one off of Ebay for $5. When it "sees" fluid, it will sink 40ma to drive a relay coil that closes the circuit on the Facet. I'm using this same setup to power a Facet transfer pump. SPST switch to power Optical sensor switch, to power relay, to power FACET and LED "On".
[quote][b]
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